This invention pertains to fuel cells and, in particular, to an assembly for controlling the temperature of such cells.
In the operation of a fuel cell, it is general practice to provide heated flue gas to the cell in quiescent state in order to bring the cell to operating temperature. Supply of the flue gas may be realized by use of an external heated supply whose output is fed to the cell through a damper which is closed by a bimetallic spring when the cell is brought to operating temperature. It also might be accomplished by disposing an electrical heater in the supply duct of the cell, again the heater being turned off when the cell operating temperature is reached.
Once the cell is brought to operating temperature, it is usually maintained there by a further temperature control system which selectively controls the amount of supply gas being delivered to the cell as well as the amount of exhausted gas being recirculated through the cell. U.S. Pat. No. 4,310,604, assigned to the same assignee hereof, discloses an assembly of this type in which a passive element in the form of a charged bellows directly senses the cell temperature and operates a damper assembly which apportions the amount of fresh supply gas and the amounts of exhausted gas carried out of the cell and recirculated through the cell in order to maintain the cell at a desired operating temperature.
While the above systems provide effective cell temperature control, research is still being conducted for improved systems of this type.
It is an object of the present invention to provide an improved temperature control system.
It is a further object of the present invention to provide an assembly for temperature control which operates to control start-up flue gas delivery as well as supply gas delivery during cell operation.
It is a further object of the present invention to provide a simple compact valve assembly for providing fuel cell temperature control from start-up to operating mode.